Illumination device for an indicating needle

Abstract

An illumination device for an indicating needle includes a plurality of light sources, an indicating needle, a guiding member, and a luminance control unit. The indicating needle includes a needle body and a needle base. The base has an entrance surface and a reflection surface. A luminance control unit controls luminance of the light sources in response to turning of the indicating needle such that the luminance is lowest when a light emitted perpendicularly from a center of an emitting surface of the light source is reflected off a reflection surface's region which a longitudinal central line of the needle body intersects with, and that the luminance gradually increases as the light emitted by the light source from the center of the emitting surface thereof is reflected off a region that is more distant from the region which the longitudinal central line of the needle body intersects with.

1. An illumination device for an indicating needle comprising:
 an indicating needle that includes a rod-shaped needle body configured to indicate an indication and a needle base whose width is larger than a width of the needle body, the needle base having an entrance surface via which a light enters an inside of the needle base and a reflection surface by which the light entering the inside of the needle base via the entrance surface is reflected toward the needle body; 
 a position detecting means for detecting a position of the needle; 
 a plurality of light sources each configured to emit the light entering the inside of the needle base via the entrance surface thereof and arranged such that the light sources encircle a driving shaft of the indicating needle; and 
 a luminance control means for controlling luminance of the plurality of light sources in response to a detected position of the indicating needle such that the luminance is lowest when the light emitted by the light source from a center of an emitting surface thereof is reflected off a region of the reflection surface that a longitudinal central line of the needle body intersects, and the luminance becomes higher when a point of reflection of the light emitted by the light source from the center of the emitting surface thereof on the reflection surface becomes more distant from the region of the reflection surface that the longitudinal central line of the needle body intersects. 
 
   
   
     2. A method for illuminating an indicating needle in a meter for a vehicle comprising the steps of:
 detecting a position of the needle; and 
 controlling luminance produced by each of a plurality of light sources for the needle which are arranged in a pattern encircling a driving shaft of the needle according to the detected needle position. 
 
   
   
     3. The method for illuminating an indicating needle as recited in  claim 2 , wherein the luminance produced by each of the plurality of light sources is controlled by controlling the duty cycle of a pulsed power supply for each of the plurality of light sources.